1. Field of the Invention
The present invention relates to an image grid data structure and an image search method using the same, and in particular to a multilevel image grid data structure having a structure of different hierarchical grid levels with respect to one color feature related to a spatial color property of a still image and an image search method for searching an image using a multilevel image grid data structure.
2. Description of the Background Art
In a conventional image search method, a feature such as a color, shape, texture, etc. is expressed in an image grid data structure of one level, and a similarity between different image data of the same structure is searched using an image grid data of one level for thereby searching the image.
When searching an image in accordance with a conventional image search method, the importance of each feature is different in accordance with the characteristics of an image which will be searched. In addition, even with respect to only one feature, the importance is different for each cell in the conventional image grid data structure. For example, in the image search method using a color histogram, which is formed in a n-dimensional structure, a weight value reflecting the importance of each element can be determined as a different value for each element forming the n-dimensional structure.
Namely, in the conventional image search method using an image data stucture of one level, the importance between features is expressed based on the corresponding grid. In this case, however, the importance for each element of a certain feature is not considered. In order to resolve this problem, another conventional image search method adopts a method for computing an average importance of the elements in a certain feature.
However, in the above-described conventional image search method, the average importance for elements of a certain features is not useful, i.e., a pre-determination of an average value for elements of a certain features is not useful in image search since the importance of each element varies by a reference image or target images.
In addition, since the conventional image grid data structure is formed of only one level, the destination contained in an image (or target image) is not accurately searched in the conventional image search method.